Extensible element



Aug 13, 1958 D, R. WRIGHT 3,396,601

EXTENS I BLE ELEMENT Filed Feb. 16, 1966 United States Patent O 3,396,601 EXTENSIBLE ELEMENT Donald R. Wright, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of' Delaware Filed Feb. 16, 1966, Ser. No. 527,835 Claims. (Cl. 74-501) ABSTRACT 0F THE DISCLOSURE An extensible boom is prepared from three sliding arms, four pulleys and a cable. The arms are positively driven.

This invention relates to an improved mechanical linkage or extensible element. It more particularly relates to an improved mechanical linkage capable of positioning a point on a predetermined line or surface.

Frequently, in the construction of buildings having curved surfaces, it is desirable to provide a guide or a tool which is readily positionable on or adjacent to a building structure in such a manner that the required design is adhered to. In cases of circular or spherical structures this is readily accomplished, for example, by pivoting an arm on the center of the desired structure. However, oftentimes it is desirable to generate structures wherein there is no ready access to the center. For example, in a spherical or spheroidal dome, often a suitable geometric center is not available or in the case of a dome having an elliptical cross-sectional configuration the centers of generation may be remote and inaccessible such as being positioned well Within the earth. Oftentimes, it is desired to support a construction unit, such as a bricklaying machine or the like, at the end of a boom or arm and position the terminal portion of the boom in such a manner that it serves as a guide and determines the final form of the structure. Such a technique is particularly advantageous when buildings are constructed from strips or portions of synthetic resinous foam which are adhered together to form the desired configuration.

It is an object of this invention to provide an improved mechanical linkage adapted to position an arm on a desired curved Surface.

A further object of this invention is to provide a mechanical linkage for an extensible element.

A further object of this invention is to provide an apparatus for the positioning of an operating mechanism in a guided pattern capable of generating a dome-like surface.

These benefits and other advantages in accordance with the present invention are achieved in an extensible el.,- ment which comprises in cooperative combination a first arm member having a first end and a second end, a second arm member having a first end and a second end, the first and second ends of the second arm being disposed generally adjacent the first and second ends of the first arm member, respectively, the second arm member being slidably af'lixed to the first arm member, a third arm member having a first end and a second end, the first and second ends of the third arm member being disposed generally adjacent the first and second ends of the second arm member, respectively; the third arm member being slidably affixed to the second arm member; a first wheel disposed adjacent the first end of the first arm member and rotatably secured thereto, a second wheel secured rotatably to the second end of the first arm member, a third wheel rotatably secured to the lfirst end of the second arm member, a fourth wheel rotatably secured to the second end of the second arm member, a flexible motion transmitting means passing about the first wheel to the second wheel, about the second Wheel to the third Wheel, about 3,396,601 Patented Aug. 13, 1968 ICC the third wheel to the fourth Wheel, and about the fourth Wheel to the first wheel, means to rotate at least one of said wheels and means to secure the motion transmitting means to the third arm member.

Further features and advantages of the present invention will become more apparent from the following speci fication taken in combination with the drawing wherein:

FIGURE 1 schematically represents an apparatus in accordance with the invention; and

FIGURE 2 is a section of the arm members of the apparatus of FIGURE 1 taken along the line 2 2.

ln FIGURE 1 there is schematically represented an embodiment of the apparatus in accordance with the present invention generally designated by the reference numeral 10. The apparatus 10 comprises in cooperative combination a first arm member 11. The first arm member 11 has a first end 12 and a second end 13. The arm member 11 has a generally elongated configuration. A first wheel, gear or drum 15 is rotatably secured to the first end 12 of the arm 11. Generally adjacent the first wheel 15 is an idler wheel gear or drum 16. The first wheel 15 has affixed thereto a rotation means or crank 17, a second Wheel 18 is rotatably afiixed to the second end 13 of the first arm 11. The first arm 11 has defined therein means 19 to slidably secure a second arm or dovetail groove. A second arm 21 is disposed adjacent the first arm 11. The second arm 21 has a first end 22 and a second end 23. The second arm 21 defines a dovetail 25 which slidably engages the dovetail groove 19 of the first arm 11 permitting the first arm 21 to be slidably secured to the first arm 11. A t iird gear 28 is rotatably affixed to the first end 22 of the second arm member 21, a fourth gear 30 is rotatably afiixed to the second end 23 of the second arm 21. The second arm 21 defines a dovetail groove 31 remotely disposed from the dovetail 25. A third arm 32 is disposed generally adjacent the second arm 21. The third arm 32 has a first end 34 and a second end 35; the third arm 32 defines a dovetail 36 which is in operative engagement with the dovetail groove 31 of the second arm 21 and operating means 37 is secured to the second end 35 of the third arm 32. When arm members 11, 21 and 32 are in maximum engagement, the first ends 12, 22 and 34 are in generally adjacent relationship and the second ends 13, 23 and 35 are in generally adjacent relationship. A flexible motion transmitting means 39 such as a cable, sprocket chain or belt passes from the first Wheel 15 to the second wheel 18, about the second Wheel 18 to the third Wheel 28, about the third wheel 28 to the fourth wheel 30, about the fourth wheel 30, to the idler Wheel 16, about the idler wheel 16, to the first Wheel 15. The motion transmitting means 39 is secured to the first end 34 of the third arm member 32 by the retaining means 41 and to the second end 13 of the first arm 11 by the retaining means 42.

In FIGURE 2 there is depicted a section of the first, second and third arms 11, 21 and 32, respectively, taken along the line 2-2 of FIGURE 1 illustrating one manner in which adjacent arms may be slidably secured to each other.

In operation of the apparatus 10 as illustrated in FIG- URE l rotation of the rst gear 15 by the operating means or handle 17 causes movement of the motion transmitting means 39 to or from the first end 12 of the first arm member 11 causing the third arm to move at a rate equal to the rate of motion of the motion transmitting means 39. The mechanical advantage presented by the second and third wheels 28 and 30 causes the second arm to move at a rate one-half of the rate of travel of the third arm 32. The apparatus 10 can be extended or retracted to about three times the length of the second or third arms. In actual practice, it is obvious that this extension will be somewhat less than three times as the arm members remain in engagement with each other.

In practical application of the apparatus 10, generally it is beneficial that it be pivotally mounted at the first end 12 of the first arm member 11 in a manner generally similar to the arm 28 of FIGURE 2 of U.S. Letters Patent 3,206,899. By controlling the motion of the first Wheel 15, the operating means 37 such as a brick laying machine or foam sealing head (which is illustrated in FIGURES 3 and 4 of U.S. Letters Patent 3,206,899) may be selectively positioned to provide a desirably shaped structure of a non-spherical design. Advantageously, domes of low profile, that is, a spherical segment having an inaccessible center, are prepared or alternately a structure having cylindrical walls and a hemispherical roof are typical examples of forms which can be prepared. Beneficially, the mechanism, in accordance with the present invention, may be utilized to advantage for such application as a ram for a charging car and other obvious applications wherein an extensible element is required.

As is apparent from the foregoing specification, the apparatus of the present invention is susceptible of being embodied with various alterations and modifications which may differ, particularly from those that have been described in the preceding specification and description. For this reason, it is to be fully understood that all of the foregoing is intended to be merely illustrative and is not to be construed or interpreted as being restrictive or otherwise limiting of the present invention, excepting as it is set forth and defined in the hereto appended claims.

What is claimed is:

1. An extensible element which comprises in cooperative combination a first arm member having a first and a second end; a second arm member having a first and second end; the first and second ends of the second arm member being disposed generally adjacent the first and second ends of the first arm member, respectively; the second arm member being slidably afiixed to the first arm member; a third arm member having a first end and a second end; the first and second ends of the third arm member being disposed generally adjacent the first and 4 second ends of the second arm member, respectively; the third arm member being slidably affixed to thesecond arm member; a first wheel disposed adjacent the first end of the first arm member and rotatably secured thereto; a second wheel secured rotatably to the second end of the first arm member; a third wheel rotatably secured to the rst end of the second arm member, a fourth wheel rotatably secured to the second end of the second arm member; a exible motion transmitting means passing about the first wheel to the second wheel, about the second wheel to the third wheel, about the third wheel to the fourth wheel, about the fourth wheel to the first wheel, means to rotate at least one of said wheels, and means securing the motion transmitting means to the first and the third arm members.

2. The apparatus of claim 1 wherein the first wheel is in cooperative combination with means to rotate the wheel.

3. The apparatus of claim 1 wherein the transmission means passing about the wheels secured to the second arm member is secured to the second end of the first arm member.

4. The apparatus of claim 1 wherein an operating means is aixed to the second end of the third arm member.

S. The apparatus of claim 1 wherein the wheels are sprocket wheels and the flexible motion transmitting means is a sprocket chain.

References Cited UNITED STATES PATENTS 459,613 9/1891 Newman 52-121 X 724,348 3/1903 Spangler 212--55 X 2,512,636 6/1950 Flynt 74-11 X 3,109,545 11/1963 Hedin 2l2-55 X 3,154,025 10/1964 Worthington 212-55 X 3,307,713 3/1967 Bopp 212-55 FRED C. MATTERN, JR., Primary Examiner.

C. F. GREEN, Assistant Examiner. 

